This study focuses on the application of a new measurement method that quantifies the residual color of filtered water using a spectrocolorimeter after filtering the discolored substances. It was confirmed through the color and turbidity cross-test that the discolored substances cannot be measured effectively with the current legal color and turbidity test method. Therefore, the National Institute of Environmental Research's filter testing method, which involves filtering the sample through 0.45 μm filter and visually inspecting the color, was improved. A membrane filter colorimetry (MFC) method was established by measuring the color difference (ΔE*ab(65)) of the filtered filter using a spectrophotometer and expressing it as filter color unit (FCU). Using the MFC method, the FCU for reference materials such as iron and manganese, as well as field samples, was measured. The results showed a high correlation with turbidity, and the color difference patterns varied depending on the type of reference materials and field samples. This indicates that the MFC method is an effective new measurement method of discolored tap water.

1. 서 론
2. 실험재료 및 방법
    2.1 시료채취 및 착색 표준물질
    2.2 분석기기 및 필터색도법 적용
3. 결과 및 고찰
    3.1 색도, 탁도 교차실험
    3.2 착색물질 원소분석
    3.3 표준물질의 필터색도법(MFC) 실험
    3.4 현장시료의 필터색도법(MFC) 실험
4. 결 론

• 김동헌(충북대학교 환경공학과, 청주시 상수도사업본부) | Dongheon Kim (Department of Environmental Engineering, Chungbuk National University, Wateworks Headquarter, Cheongju City)
• 이종금(청주시 상수도사업본부) | Jonggeum Lee (Wateworks Headquarter, Cheongju City)
• 오지윤(청주시 상수도사업본부) | Jiyoon Oh (Wateworks Headquarter, Cheongju City)
• 김기태(청주시 상수도사업본부) | Gitae Kim (Wateworks Headquarter, Cheongju City)
• 전항배(충북대학교 환경공학과) | Hangbae Jun (Department of Environmental Engineering, Chungbuk National University) Corresponding author